Balkan Workshop BW2013 Beyond the Standard Models 25 – 29 April, 2013, Vrnjačka Banja, Serbia

1. Daniela Kirilova
Institute of Astronomy and NAO
Bulgarian Academy of Sciences, Sofia, Bulgaria
SEENET-MTP Workshop: Beyond the Standard Models - BW2013
Vrnjacka Banja, Serbia, April 25 -29, 2013

2. Astrophysical and cosmological observations data – necessity
of BSMs physics
The contemporary LCDM contains already considerable
DE+DM, unknown nature components constitute 95% of Universe matter!
Inflation, Baryon Asymmetry, etc.
to understand these puzzles physics BSM is required
to propose the DM, DE, inflaton candidates , etc
OR
change the theoretical basis of SCM (alternative grav. theory, etc.)
Neutrino : experimental data firmly established physics BSMs
SMs assumptions: m=0, Neff=3, L=0, equilibrium FD distribution
. Neutrino oscillations expt challenged all these
This talk : some neutrino characteristics BSM
their cosmological effects and constraints

3. Relic neutrino predicted by SCM
Neutrino beyond SMs
neutrino oscillations, non-zero masses
inert neutrino, distortions
Leptogenesis by neutrino oscillations
BBN - the Early Universe Probe and SMP Test
Cosmological Effects and BBN Constraints on Neutrino
Oscillations
Cosmological Effects and BBN Constraints on L
Change of constraints in case of L or/and inert neutrino
Excess radiation density in the Universe? eV neutrino saga
Possible explanations: extra particles, mixing, decays, L

4. Decoupling. Characteristics expected.

5. Tν = Te = Tγ
T1 MeV equilibrium neutrinos due to weak interactions
CNB Formation in SCM
At RD stage neutrinos are important component, influence considerably H,
n-p kinetics, etc.
2 2
~ F EГ NG  
2
~ TGgH eff
Neutrinos from CNB are expected to be the most numerous particles after CMB photons.

-
αα
-
α
-
α
βαβα
βαβα
ee
ee





νν
νν
νννν
νννν
Tdec(νe) ~ 2 MeV Tdec(νμ,τ) ~ 3 MeV
T~me, photons were heated T=(4/11)1/3 Tcmb
γγ -
ee
n  339.3 cm-3
0
2 2
3
93.14 eV
m
h
 
1e
1
T)(p,f p/T

 

2.984 0.008 (LEP)N  
T ~1 MeV As the Universe cools the rate of interaction decrease and could no longer keep
neutrino in equilibrium.
N = 3.046 not 3
RELIC NEUTRINO BACKGROUND
Since decoupling neutrino were free streaming, i.e. cosmological neutrino background.
Since Tdec(ν) is close to me, neutrinos shared a small part of the entropy release
Neutrino oscillations account slightly change neutrino particle and energy densities
Dolgov, Hansen & Semikoz,1997,Mangano et al,02,05
0
2 2
3
94.12 eVc
m
h




  
n  335.7 cm-3



6. Though numerous, CNB direct detection is very difficult because it is an
extremely elusive particle due to its weak interactions and extremely low
energy expected for neutrinos today.
Figure from ASPERA roadmap
Indirect CNB detection is possible due to its effect on BBN,CMB, LSS.
CMB&LSS feel the total neutrino density. BBN is precise probe also of neutrino
energy distribution, mass differences and mixing, chemical potential, etc.
0
2
3
93.14 eV
m
h
 
-3
339.3 cmn 
0.001 0.02  
T0~ 1.9 K.

7. Neutrino in Standard Cosmological Model
• massles
• Neutrino spectra have the equilibrium Fermi-Dirac distribution (an assumption).
• The lepton asymmetry is zero (an assumption).
 Neutrino contribution to the energy density of the Universe
Effective number of relativistic
neutrino species
exp( / )/(1 exp( / ))eq
n E T E T    
• Neff is ~ 3 (for standard neutrinos if non-instantaneous decoupling is considered, Neff =3.046).

8. Neutrino, though negligible today
was an important constituent of the Early Universe

9. Effect the energy density
expansion rate
of the Universe
Effect BBN kinetics
Spectrum distortion
asymmetry constraints
Effect on CMB and LSS
Constraints on number
of neutrino species
Constraints on neutrino masses
and number densities < 0.66 eV
Matter/radiation equality shift
Constraints on
oscillation parameters
Constraints on
sterile neutrino population
Feel total energy density
stored in neutrinos
Constraints on neutrino masses
Constraints on lepton asymmetry
not sensitive to different species
or spectrum distortions

10. Deviations from Fermi-Dirac distribution
• Electron-positron annihilation – negligible effect
• Flavor oscillations Dolgov 1981 ;Mangano et al, 2005
number density of one neutrino species 113 per cubic cm instead 112 in SCM.
Flavor oscillations with parameters favored by the atmospheric and solar neutrino data
establish an equilibrium between active neutrino species before BBN epoch.
• Non-zero lepton asymmetry Terasawa, Sato 88; Wagoner et al.
Neutrino-antineutrino asymmetry – now strongly constrained by BBN in all
sectors because of flavor oscillations <0.1 Dolgov et al. 2002
• Active-sterile oscillations before neutrino decoupling slightly influence active
neutrino distributions, because the states are refilled due to interactions with
the plasma and may bring sterile neutrino into equilibrium.
• Active-sterile oscillations proceeding after decoupling may strongly distort
neutrino energy spectrum DK, 1988; DK&Chizhov PLB 97
• Decays of neutrino and into neutrinos
• Violation of spin statistics, etc. Dolgov ,Smirnov ,PLB,2005; Barabash et al., 2007

11. Neutrinos Oscillations
Solar neutrino problem, atmospheric neutrino anomaly
and the results of terrestrial neutrino oscillations
experiments were resolved by the phenomenon of
neutrino oscillations.
It has been observationally and experimentally proved
that neutrinos oscillate. BSM characteristics for it hold:
 non-zero neutrino mass and mixing
 Distribution n(E) of neutrino may
differ from the equilibrium FD form
 L may become considerable
in resonant active-sterile oscillations
additional species may be brought into equillibrium
 sterile neutrino
m2  0 at least 2 neutrino with m  0
m = Umf f, (f = e, , )
P (, m2, E, t)
Ne < Neq
0
2
3
93.14 eV
m
h
  0.001 
Flavor neutrino should not play an important
role for DM (because it is HDM) and the
formation of structure.
Eventual sterile neutrino may be a good DM
representative (CDM, WDM).
0.001 0.02  
exp( / )/(1 exp( / ))cnb eq
n n E T E T     
Neutrino anomalies are well described in terms of flavor neutrino oscillations, but sub-
leading sterile oscillations may provide better fit.

12. Propagation of neutrino in early Universe
• The thermal background of the early Universe influences the propagation of ν.
Differences in the interactions with the particles from the plasma lead to different
average potentials for different neutrino types Vf f= e, μ, τ
Notzold&Raffelt 88 In the Sun L>>Q/M
2
w
Vf =QT3/(M2
wδm2 ) -L T3 /δm2 for neutrino
Vf =Q…. +L ……… for antineutrino
Q=-bET L=-aLα
• In the early Universe, at E>10 MeV, Q>L if L is of the order of B.
In the adiabatic case the effect of the medium can be hidden in matter oscillation
parameters:
In general the medium suppresses oscillations.
When mixing in matter becomes maximal
independent of mixing in vacuum - enhanced oscillation transfer.
for Q/M2
W>L δm2 <0 resonant oscillations both for neutrino and antineutrino
for Q/M2
W<L at δm2 <0 resonant for antineutrinos, δm2 >0 – for neutrinos
2 2 2 2 3 2 2
sin sin /[sin (( / ) / cos 2 ) ]Wm Q M L T m       
2 3 2
( / ) cos 2WQ M L T m 

13. Evolution of oscillating neutrino е  s
     2
0 2
( ) ( )
, ( ) 2 , ( )F F
W
t t Q
Hp i t i G L N t O G
t p M
 

 
  
  
      
   
H
 
    
*
3
, ,
~ ~ 2 ~ /
1 0
exp / 1 exp /
0 0
e e
ie je i il l
LL LL
in eq in eq
LL
U U U l e s
is free neutrino Hamiltonian
Q E T L L L L L d p N
n E T E T n
      
   
  
 
 
  
  
 
       
 

0H
Approach: follow the evolution of neutrino for each momentum; account for oscillations,
expansion and interactions with the medium simultaneously DK 1988, Chizhov, DK, 1997

14. Oscillations in the Early Universe medium
• The thermal background of the early Universe influences the propagation of ν.
Differences in the interactions with the particles from the plasma lead to different
average potentials for different neutrino types Vf f= e, μ, τ
Notzold&Raffelt 88 In the Sun L>>Q
Vf =Q-L for neutrino
Vf =Q+L for antineutrino
Q=-bET4 /(δm2M2
W) L=-aET3Lα/(m2)
• In the early Universe, E>10 MeV, Q>L if L is of the order of B.
In the adiabatic case the effect of the medium can be hidden in matter oscillation
parameters:
In general the medium suppresses oscillations.
When mixing in matter becomes maximal independent of mixing in
vacuum - enhanced oscillation transfer.
for Q>L δm2 <0 resonant oscillations both for neutrino and antineutrino
for Q<L at δm2 <0 resonant for antineutrinos, δm2 >0 – for neutrinos
2 2 2 2
sin sin /[sin ( cos 2 ) ]m Q L      
cos 2Q L  

15. BSM neutrino: nonequilibrium neutrino
 Active-sterile oscillations considerable cosmological influence
 Dynamical effect: Excite additional light particles into equilibrium
~geffT4
Fast a  s effective before a decoupling - effect CMB and BBN through increasing  and H
He-4 mass fraction is a strong function of the effective number of light stable
particles at BBN epoch Yd ~0.013 Ns (the best speedometer).
Dolgov 81, Barbieri &Dolgov 90, Kainulainen 91, Enqvist et al.,92
 Distort the neutrino energy spectrum from the equilibrium FD form
DK 88, DK&Chizhov 96
 Change neutrino-antineutrino asymmetry of the medium (suppress / enhance)
Foot&Volkas 95,96; DK&Chizhov 96,97,2000
DK&Chizhov 98,2000, Dolgov&Villante 03, DK04,07 ,DK&panayotova, 2006, DK07
Active-sterile oscillations may play crucial role for neutrino involved processes in
the Universe during BBN, CMB, LSS, CNB.
sN
2
~ TGgH eff
7
10.75 3
4
eff ssg N N N   
2 2
~ F EГ NG  
He-4 depends on the e characteristics: e decrease  n/p freezes earlier 
4Не is overproduced
BBN is a sensitive probe to additional species and to distortions in the neutrino
distribution.
BBN stringent limits on oscillation parameters.

16. • Active-sterile oscillations proceeding after decoupling
may strongly distort neutrino distribution and deplete electron neutrino.
Kirilova 88, Kirilova&Chizhov PLB,97
2 neutrino mixing: Sterile state is filled for the sake of e
Precise description of neutrino momenta distribution:
1000 bins used to describe it in non-resonant case
up to 10 000 in the resonant case.
Energy spectrum distortion caused by oscillations depends on the
level of initial population of s.
Kirilova,IJMPD,2004
2 4 7
sin 2 10m  

exp( / )/(1 exp( / ))eq
n E T E T    
Nk,4 < Nk,2
Flavor mixing decreases the depletion and spectrum distortion

17. L oscillations interplay
 Neutrino active-sterile oscillations change neutrino-antineutrino asymmetry of the medium
suppress pre-existing asymmetry Barbieri&Dolgov 90.91; Enqvist et al. 1992
enhance L (MSW resonant active-sterile oscillations) L-T=M
Kirilova&Chizhov 96; Foot&Volkas 96 -L-T=M
L enhancement in MSW resonant active-sterile neutrino oscillations was first found for
m2
>10-5
eV2
in collisions dominated oscillations Foot, Thompson&Volkas 96
m2
<10-7
eV2
in the collisionless case Kirilova&Chizhov “Neutrino 96”
Flavor oscillations equalize L in different flavors before BBN Dolgov et al., NPB, 2002
 Relic L effects neutrino oscillations
suppresses them Foot&Volkas, 95; Kirilova&Chizhov 98
enhances them Kirilova&Chizhov 98
2
( , , , ,..)m m L T  
In BBN with neutrino oscillations spectrum distortion and L generation lead to
different nucleon kinetics, and modified BBN element production.

19. Strong influence because of the nearby
epochs in the universe history
Processes cosmic time T
GUT 10-35 s 1015 GeV
Inflation
BA generation
EW symmetry breaking 10-10 s 100 GeV
QCD 10-5 s 0.3 GeV
CNB formation 1 s 3 - 1 MeV
BBN 1 s – 3 m 1 - 0.1 MeV
CMB formation 300 000 y 0.3 eV
Galaxy formation ~109 y
Today 13.7 109 y 0.0003 eV
~ 3K

20. 2.8 ≤ N ≤ 3.6 (95% CL)
Iocco et al, 2009
Using Y from IT10:
3.0 ≤ N≤ 4.5 (95% CL)
Big Bang Nucleosynthesis
Theoretically well established
Precise data on nuclear processes rates
from lab expts at low E (10 KeV – MeV)
Precise data on D, He, Li
Baryon fraction measured by CMB
Most early and precision probe for physical conditions
in early Universe and for new physics at BBN energies.
The Best Speedometer at RD
BBN probes BSM neutrino (oscillations, nonequilibrium)
The Most Exact Leptometer
COSMOLOGY
ASTROPHYSICS
MICROPHYSICS

21. • D is measured in high z low-Z H-rich
clouds absorbing light from background QSA.
• He in clouds of ionized H (H II regions),
the most metal-poor blue compact galaxies.
• Li in Pop II (metal-poor) stars in the spheroid
of our Galaxy, which have Z<1/10 000 Z ☼.
The Abundances of Light Elements
D/H=(2.87±0.22) 10-5
Main problem: Primordial abundances are not
observed directly (chemical evolution after BBN).
Observations
in systems least contaminated by stellar evolution.
D from Iocco et al. PR472, 1 (2009); He from Aver et al.
2012
Yp=0,2534 0,0083
regression to zero Z
BBN is the most early and precision cosmology probe for physical conditions in the
early Universe, and for constraining new physics, relevant at BBN energies.

22. According to BBN 4 light elements: D, He-3, He-4, Li-7
produced during the hot stage of the Universe evolution,
1 s – 3 m 1 - 0.1 MeV.
10 9
~10 10 KT 
The primordially produced abundances depend on:
 baryon-to-photon ratio (CMB measured now),
 relativistic energy density (effective number of nu)
(nonst interactions, extra rel degrees of freedom, exotic physics)
 n lifetime
BBN is sensitive baryometer, speedometer
and leptometer. BBN probes neutrino properties,
non-standard physics, early Universe
BBN predictions are in agreement with
observational data for ΩB ~ 0.05.
Observational data (2σ error). Vertical band give baryon
density measured by CMB.
4/3
7 4
(?)
8 11
X N    
 
   
 

23. BBN constrains physics beyond SM
• BBN depend on all known interactions - constrains modification of those
• Additional light (relativistic during BBN, i.e. m< MeV) particles species
(generations) effecting radiation density (H), pre-BBN nucleon kinetics or
BBN itself
• Additional interactions or processes relevant at BBN epoch (decays of
heavy particles, neutrino oscillations)
• Depart from equilibrium distributions of particle densities of nucleons and
leptons (caused by nu oscillations, lepton asymmetry, inhomogeneous
distribution of baryons, etc.)
• ……………..

25. 4Не – sensitive speedometer
sn 7,885e n p e 
  
epne ~
MeVm 293.1
52
~ TGГ F
2
~ TGgH eff
MeV
G
Gg
T
F
eff
f 7,0~~
6/1






75,10
4
7
2
11
 Ngeff
6
1
~~ fT
m
f
e
p
n








 
f
f
fnuc
n
fn
p
n
p
n
N
N
X




















1
  24.0~2 n
t
fnp eXY 


~ 
epn
Yт=(H((g)),) = 0,2482 0,0007
Yо=0,256 0,01
He-4 most abundantly produced (25%), most precisely measured
(3-5 %) and calculated element (0.1% error), has simple post-BBN evolution
YКН~0.013 Nеff
4Не is the best speedometer at BBN. Constrains additional radiation.
Shvartsman 1969

26. BBN Speedometer
2.8 ≤ N ≤ 3.6 (95% CL)
Iocco et al, 2009
Using Y from IT10:
Yp=0,2565  0.001(stat) 0,005(syst)
Izotov&Thuan, 2010 93 Sp of 86 low Z HII
3.0 ≤ N≤ 4.5 (95% CL)
Increasing Δ Nеff mirrors increase inYp
Nеff =3.53+0.66
-0.63 (CMB, D)
Nollett&Holder,2011

27. BBN constraints
• Constrains the effective number of relativistic species
Non-zero ΔNeff will indicate any extra relativistic component:
like sterile neutrino, neutrino oscillations, lepton asymmetry,
neutrino decays, nonstandard thermal history, etc
Steigman 2012 1208.0032
Y=0.2565  0.006 Δ Nеff =0.66 0.46 consistent with ΔNеff =0 95% C.L.
Nеff =3.71+0.47
-0.45 ΔNеff ~1 favored ΔNеff ~2 disfavored at > 95% C.L.
Untill Plank CMB larger errors for ΔNeff than BBN
Planck Collaboration arXiv: 1303.5076
Planck: Nеff =3.361+0.68
-0.64 (95% Planck +WP+high l)
Nеff =3.30+0.54
-0.51 (95% Planck +WP+high l+BAO)
Nеff =3.52+0.48
-0.45 (95% Planck +WP+high l+H0+BAO)
CMB Tension b/n H direct measurements and CMB and BAO data relieved
if extra radiation exists, best fit : Nеff =3.37 (for low l power sp)
4
Y~0.013 Nеff

28. CMB+BBN simultaneous constraints
Simultaneous constraints on Y and N:
Nеff =3.41+0.3
-0.3 (68% Planck +WP+high l+Y(aver et al.))
Nеff =3.02+0.27
-0.27 (68% Planck +WP+high l+D(Pettini+Cooke))
Nеff =3.33+0.59
-0.83 (68% Planck +WP+high l)
Yp=0.254+0.041
-0.033

29. CMB+BAO simultaneous constraints
However, simultaneous constraints on Nеff and the total neutrino mass
or sterile neutrino mass:
• massless sterile
Bounds tighten when BAO data are added:
• massive sterile (MiniBoone, reactor and Gallium anomalies), mn=0.06 eV
Bounds marginally compatible with fully thermalized sterile neutrino with sub-eV
mass <0.5 eV necessary to explain oscillations anomalies
L needed to suppress thermalization of the sterile neutrino
Nеff =3.29+0.67
-0.64 (95% Planck +WP+high l)
Smn<0.60 eV
Nеff =3.32+0.54
-0.52 (95% Planck +WP+high l+BAO)
Smn<0.28 eV
Nеff <3.91 (95% Planck +WP+high l for thermal sterile m<10 eV)
mns<0.59 eV

30. BBN constraints
Non-zero ΔNeff indicate lepton asymmetry:
 Constrains lepton asymmetry
Steigman 2012 1208.0032
consistent with L=0 at 1.5 s
|x|<0.09 at 2 s ΔNeff
L ~ <0.011 at 2 s
x=0.038 0.026 allowed by He abundance, deviation from x=0 1.5 s
No new physics, no dark radiation, no L
CMB not sensitive to such small L.
……………………………..
4
4 2
effN =15/7[([ /T)/ ] +2[( /T)/ ] }   
YКН~0.013 Nеff
• Constrains neutrino oscillations parameters
BBN with   s neutrino spectrum and densities differ, thus influencing kinetics of
nucleons in BBN epoch, reducing weak processes rates overproducing He-4.
The abundance of helium is known with 5% accuracy. This allows to constrain   s

31. Neutrino Oscillations Effects
 Active-sterile oscillations a  s may have considerable cosmological
influence!
 Dynamical effect: Excite additional light particles into equilibrium
~geffT4
Fast a  s effective before a decoupling - effect CMB and BBN through increasing  and H
He-4 mass fraction is a strong function of the effective number of light stable
particles at BBN epoch Yd ~0.013 Ns (the best speedometer).
Dolgov 81. DK 88, Barbieri, Dolgov 90, Kainulainen 91, Enqvist et al.,92
 Distorting the neutrino energy spectrum from the equilibrium FD form
DK 88, D.K&Chizhov,96
 Change neutrino-antineutrino asymmetry of the medium (suppress / enhance)
D.K&Chizhov,96; Foot&Volkas 95,96; Shi 96; di Bari 2003; DK 2012
DK&Chizhov 98,2000, Dolgov&Villante 03, DK04,07;DK&Panayotova 06 ;Panayotova 2011, DK 2012
2
~ TGgH eff
7
10.75 3
4
eff ssg N N N   
2 2
~ F EГ NG  
He-4 depends on the e characteristics: e decrease  n/p freezes earlier 
4Не is overproduced
BBN is a sensitive to additional species and to distortions in neutrino distribution
BBN stringent limits on oscillation parameters.
 Flavor Matter Oscillations favored by the atmospheric and solar neutrino data
establish an equilibrium between active neutrino species before BBN epoch.
No considerable influence on BBN, CMB, CNB.
Account for flavor oscillations : 113 /cm3 instead 112 in SCM. But might be important for L.

32. Sterile neutrinos may be present at the onset of BBN epoch - may be produced in GUT models, in models with
large extra dimensions, Manyfold Universe models, mirror matter models, or by oscillations in 4-neutrino mixing
schemes, etc. The degree of population may be different depending on the production model.
The distortion due to active-sterile oscillations and the kinetic effect caused Nk
depends on the degree of initial population of s. The biggest effect Nk,0 is achieved
for Ns=0, the effect decreases with Ns .
Nk ~ Nk,0- Nk,0 Ns
Spectrum distortion for non zero initial popuation of s
Spectrum distortion for different initial population of s.:
Ns=0 – lowest curve, Ns=0,5 and Ns=0,8 – upper curve.
The dashed curve shows the equilibrium spectrum.
DK,Int.J.Mod.Phys.D,2004
Ns=0,8
Ns=0,5
Ns=0
Due to nonequilibrium oscillations the number
density of neutrinos are depleted and their
distribution differ from equilibrium FD one.

33.  Maximum He-4 overproduction in BBN with active-sterile
neutrino oscillations may be much bigger than 5% due to
kinetic effects.
BBN with nonequilibrium es allows to
constrain  oscillation parameters for
He-4 uncertainty up to 32% (14%) in resonant
(non-resonant) case.
BBN with ne ns leads to max 4Не overproduction
32% in the resonant case (13% in the non-resonant)
i.e. 6 times stronger effect than the dynamical
oscillations effect. DK , Astrop.Phys.,2003
 The kinetic effects of oscillations depend on the initial
population of neutrino due to interplay b/n effects
Role of sterile neutrino: dynamical effect– increasing Н(g)
suppressing the osc kinetic effect
N= Nk,0- Nk,0 Ns +Ns

34. He-4 is the preferred element:
 abundantly produced,
 precisely measured
 precisely calculated (0.1% uncertainty)
Yp=0,2482 0,0007
 has a simple post-BBN chemical evolution
 best speedometer and leptometer
 sensitive to neutrino characteristics (n, N, sp,LA..)
Fit to BBN constraints corresponding to Yp/Yp=3%:
BBN with nonequilibrium oscillations leads up
32% He overproduction, i.e. N<9.
BBN with oscillations may provide the excess density.
BBN constraints on e s
DK, Chizhov NPB2000,2001;
 
42 2 9 2 2
2 10 2 2
sin 2 1.5 10 0
8.2 10 large , 0
m eV m
m eV m
  
  


  
  
Yp=0,2565  0.001(stat) 0,005(syst)
Izotov&Thuan, 2010 93 Sp of 86 low Z HII

35. BBN constraints on oscillations
BBN with neutrino oscillations between initially empty s and e
Barbieri, Dolgov 91 – depletion account
Dolgov 2000 – dashed curve;
DK, Enqvist et al. 92 – one p approx.
Dolgov, Villante, 2003 - spectrum distortion
 
 
22 4 5 2
22 4 5 2
sin 2 3.16 10
sin 2 1.74 10
es es
s s
m eV N
m eV N

  
 
 


  
  
DK.,Chizhov 2001 – distortion and
asymmetry growth account
 
42 2 9 2 2
2 10 2 2
sin 2 1.5 10 0
8.2 10 large , 0
m eV m
m eV m
  
  


  
  
 BBN constraints are by 4 orders of magnitude more stringent than experimental ones
 Excluded 2 of the possible solutions of the solar neutrino problem : LMA and LOW active-sterile
solutions (1990, 1999)
years before experimental results.
 Excludes electron-sterile solution to LSND
2 4 7
sin 2 10m  

BBN constraints on е  s :
m2>10-6 eV2

36. BBN constraints relaxed or strengthened?
Additional s population may strengthen or relax BBN constraints.
Yp/Yp=5.2%
Dotted blue (red) contour presents Yp/Yp=3% (Yp/Yp=5.2% )
for Ns=0 dotted curve, solid - Ns=0,5.
Due to interplay b/n the effects of
non-zero initial population of s (partially
filled) on BBN,
BBN bounds change non-trivially with Ns:
In case the dynamical effect dominates,
He-4 overproduction is enhanced and
BBN constraints strengthen.
In case the kinetic effect dominates He-4
overproduction decreases with Ns increase and
BBN constraints relax.
Yp=0,2565  0.001(stat) 0,005(syst)
Izotov&Thuan, 2010 93 Sp of 86 low Z HII
Yth=0,2482 0,0007
DK&Panayotova JCAP 2006;DK IJMPD 07,Panayotova 2011;DK,2011
Constraint contours for 3 and 5% He-4 overproduction

38. Lepton Asymmetry
Lepton asymmetry of the Universe
may be orders of magnitude bigger than the baryon one,
Though usually assumed L~, big L may reside in the neutrino sector
(universal charge neutrality implies Le=) .
CNB has not been detected yet, hence L may be measured/constrained only indirectly
through its effect on other processes, which have left observable traces in the Universe:
light element abundances from Big Bang Nucleosynthesis , CMB, LSS, etc.
Wagoner et al.1967….Terasawa&Sato, 1988 …
Dolgov,2002
Serpico&Raffelt, 2005; Pastor, Pinto&Raffelt,2009; Simha&Steigman, 2008
Lesgourgues&Pastor,1999; Shiraishi et al., 2009; Popa&Vasile, 2008
10
( )/ ~ 6.10b b
n n n 
 
( )/l l
L n n n 
3
3 2
3
1
( )
12 (3)
i
i ii
T
L
T

 

  

  /T 
~
ii
L L

39. Lepton Asymmetry Effects
• Dynamical - Non-zero L increases the radiation energy density
leading to faster expansion H=(8/3G)1/2, delaying matter/radiation equality epoch …
influence BBN, CMB, evolution of perturbations i.e. LSS
• Direct kinetic - |Lne|> 0.01 effect neutron-proton kinetics
in pre-BBN epoch
influence BBN, outcome is L sign dependent
Simha&Steigman, 2008:
• Indirect kinetic - L  10-8 effects neutrino evolution, its number density, spectrum
distribution, oscillations pattern and hence n/p kinetics and BBN
DK&ChizhovNPB98,2000;DK PNPP, 2010, 2011, DK JCAP,2012.
• L changes the decoupling T of neutrino, etc.
4 2
effN =15/7(( / ) +2( / ) )   
e n p e 
  
epne ~
~ 
epn
10~ (0.2482 0.0006) 0.0016 0.013 0.3 ep effY N      

40. BBN Constraints on L
 BBN provides the most stringent constraint on L
In case neutrino oscillations degeneracies equilibrate
due to oscillations before BBN
Dolgov et al., NPB, 2002
Serpico&Raffelt,2005 role
Iocco et al.,2009
 Accounting for flavor oscillations and ν decoupling
and Miele et al.,2011
 Steigman, 2012 recent analysis
|x|<0.09 at 2 s consistent with L=0 at 1.5 s
x=0.038 0.026 allowed by He abundance, deviation from x=0 1.5 s
 CMB and LSS provide looser bounds
L(x) modifies the power spectra of radiation and matter Lesgourgues&Pastor, 99
Popa&Vasile , 2008 forcast for Planck:
Interplay between L and active-sterile oscillations allows to constrain strongly L.
| | 0.1 
2
13sin 0.03  0.1L 

41. Asymmetry - Oscillations
Interplay
 Neutrino active-sterile oscillations change neutrino-antineutrino asymmetry of the medium
suppress pre-existing asymmetry
Barbieri&Dolgov 90.91; Enqvist et al. 1992
enhance L (MSW resonant active-sterile oscillations) L-T=M
-L-T=M
L enhancement in MSW resonant active-sterile neutrino oscillations was first found for
m2
>10-5
eV2
in collisions dominated oscillations Foot&Volkas 96
m2
<10-7
eV2
in the collisionless case Kirilova&Chizhov 96
 Asymmetry effects neutrino oscillations
suppresses them
Foot&Volkas, 95; Kirilova&Chizhov 98
enhances them
Kirilova&Chizhov 98 ; Kirilova 2010, 2012
2
( , , , ,..)m m L T  

42. We studied the interplay between small L and neutrino oscillations in the early
Universe and their effect on BBN for the specific case:
effective after active neutrino decoupling
Small L<<0.01 influence indirectly BBN via oscillations by:
 changing neutrino number densities
 changing neutrino distribution and spectrum distortion
 changing neutrino oscillations pattern (suppressing or enhancing them)
L effect in density and direct effect in n-p kinetics – negligible
• Different cases of L were studied:
relic initially present L>10-10 and dynamically generated by oscillations
1 = ecos + ssin
2 = - esin + scos
2 4 7
sin 2 10m  
 eV2
Foot&Volkas 97, Bell,Volkas&Wang,99
DK&Chizhov , NPB 96, 98, 2001 DK PNPP 2010
The evolution of the L was numerically studied. L influence on oscillations was explored
in the full range of model oscillation parameters and a wide range of L values.
Primordial production of He-4 was calculated. Modified BBN constraints on oscillation
parameters in presence of L were presented.

43. Evolution of neutrino in presence of
е  s oscillations and L
• Equations governing the evolution of the oscillating  and s , accounting
simultaneously for Universe expansion, neutrino oscillations and neutrino forward
scattering.
     2
0 2
( ) ( )
, ( ) 2 , ( )F F
W
t t Q
Hp i t i G L N t O G
t p M
 

 
  
  
     
   
H
     2
0 2
( ) ( )
, ( ) 2 , ( )F F
W
t t Q
Hp i t i G L N t O G
t p M
 

 
  
  
      
   
H
 
    
*
3
, ,
~ ~ 2 ~ /
1 0
exp ( )/ 1 exp ( )/
0
e e
ie je i il l
LL LL
in eq in eq
LL
s
U U U l e s
is free neutrino Hamiltonian
Q E T L L L L L d p N
n E T E T n
N
      
     
  
 
   

  
  
 
         
 

0H
7
10.75 3
4
eff ssg N N N   
Non-zero L term leads to coupled integro-differential equations and hard numerical task .
L term leads to different evolution of neutrino and antineutrino.

44. Evolution of nucleons in the presence of е  s
)()(),,(
2
LLnpe
n
n
n
p
nnnnpeAped
p
n
Hp
t
n
 








)()~()~,,(
2
LLpne
nnnpneAped   


2 7 2
10 0 1
2 0.3
sm eV all mixing angles N
MeV T MeV
  
  
 
Oscillations and L dynamical and
kinetic effect on BBN were explored.
Y ~0.013 NN= Nk,0- Nk,0 Ns +Ns
 In BBN with e s and L neutrino spectrum distortion and the density of electron
neutrino may considerably differ from the standard BBN one, leading to different nucleon
kinetics, and modified BBN element production.
10-10<L<0.01
BBN with е  s and L

45. Oscillations generated L and BBN
For m2
sin4
2 <10-7
eV2
evolution of L
is dominated by oscillations and typically
L has rapid oscillatory behavior.
The region of parameter space for which
large generation of L is possible:
Generation of L up to 5 orders of magnitude
larger than  is possible, i.е. L~10-5
evolution.
2 0.5
sin 2 10 

25.942
102sin|| eVm 

L(t)
m2
~10-8.5
eV2
 In BBN with e s neutrino spectrum distortion
and asymmetry generation lead to different nucleon
kinetics, and modified BBN element production.
)()(),,(
2
LLnpe
n
n
n
p
nnnnpeAped
p
n
Hp
t
n
 








)()~()~,,(
2
LLpne
nnnpneAped   


2 7 2
10 0 1
2 0.3
sm eV all mixing angles N
MeV T MeV
  
  
 
-3,0 -2,5 -2,0 -1,5 -1,0 -0,5 0,0
0,13
0,14
0,15
0,16
0,17
m
2
=10
8.65
eV
2
Xn
log(sin
2
2)
m
2
=10
7
eV
2
Xn and correspondingly the primordially produced
He-4 decreases at small mixing parameters values
due to asymmetry growth.
DK, PNPP,2010; 2011

46. Effect of dynamical L and distortion of е distribution on constraints
Thus, if the mixing is small the generated asymmetry may partially suppress
the oscillations and the inert neutrino may equilibrate only partially .
 The account of the neutrino-antineutrino
asymmetry growth caused by resonant
oscillations leads to relaxation of the
BBN constraints for small mixings.
 The spectrum distortion leads to a decrease
of the weak rates, to an increase of the n/p
freezing T and He overproduction.
Correspondingly the account of spectrum
distortion leads to strengthening of BBN
constraints at large mixings by orders of
magnitude.
Oscillations change energy spectrum distribution and the number densities of е from
standard BBN case. This influences the kinetics of nucleons during BBN and changes the
produced light element abundances.
Ns=0

47. Relic L and BBN with oscillations
BBN with oscillations is the best known leptometer.
suppresses oscillations
inhibit oscillations.
L change primordial production of He
by enhancing or suppressing oscillations.
2 2/3
0.1( )L m
2 2/3
( )L m
 2
, ,pY m L 
Lepton asymmetry may relax BBN constraints
at large mixings and strengthen them at small
mixing. DK&ChizhovNPB98, Kirilova JCAP 2012
DK, JCAP 2012 BBN with oscillations can feel extremely small L: down to 10-8
2 2 3/2
( )m eV L 

48.  Cosmological indications suggesting additional relativistic density:
NBBN=3.8+0.8-0.7 NCMB=4.34+/- 0.87 NSDSS=4.78+1.89-1.79
Y=0.2565+/-0.001+/-0.005 WMAP7+BAO+HST Komatsu et al. 2011
A IT2010 68% CL 95% confidence
Y=0.2561+/-0.01 Aver et al. 2010
WMAP7+BAO+HST+ACT Keisler et al. 2011: 3.86+/-0.42
+SPT Dunkley et al. 2011 4.56+/-0.75
Neutrino oscillations expts indications
ΔNeff measures any relativistic component, including inert
neutrino brought into equlibrium, oscillations, LA, decays,
etc.
CMB recent data does not require DR. Neutrino exp data analysis point to 3+1, do not
need 3+2 models anymore, in light of recent expt results.

49. Fruitful interplay b/n cosmology and particle physics exists.
 Cosmology can predict the influence of BSM neutrino characteristics and test them. In
particular, it «measures» total neutrino mass, number of neutrino species, neutrino
hierarchy (hopefully), neutrino oscillations patameters, deviations from equilibrium, ..
 In case of active-sterile oscillations effective after decoupling of active neutrinos
the number densities of CNB neutrinos may be reduced, the spectrum distorted
 BBN is very sensitive to neutrino spectrum distortion and lepton asymmetry.
BBN constraints on oscillations parameters in case of non-equilibrium oscillations
do exist even if He-4 uncertainty were over 5%. Spectrum distortion plays a major
role in the influence of neutrino oscillations on BBN.
BBN provides the most stringent constraint on m2 .
BBN bounds on Neff is strengthened in case of neutrino oscillations.
 BBN constraints on neutrino oscillations parameters depend nontrivially on the
population of sterile neutrino and L in the Universe.
BBN bounds on L depend on the presence of neutrino oscillations. They
strengthen considerably in case of presence of active- sterile neutrino oscillations.
BBN bounds on Neff is strengthened in case of neutrino oscillations.
• Additional initial population of the sterile state not always leads to strengthening of
constraints (as can be naively thought) it may also relax them.
Summary
Cosmology Tests and Predictions of BSM neutrino characteristics

50.  Considerable L generation in active-sterile Mikheyev-Smirnov-Wolfenstein
oscillations, effective after neutrino decoupling, is found. The region in the oscillation
parameter space of considerable L growth was determined.
 Small lepton asymmetry LA << 0.01, either relic or generated by active-sterile
neutrino oscillations, which do not have direct effect on nucleons kinetics during
BBN, may have considerable cosmological influence. Such small asymmetries are
invisible by CMB, but may be felt by BBN: L as small as 10-8 may be felt by BBN
via oscillations.
 The effect of the dynamically generated and initially present L on BBN with
oscillations was studied. Lepton asymmetry is able to enhance, suppress or inhibit
oscillations. The parameter range for which relic L is able to enhance, suppress or
inhibit oscillations is determined.
 L provides relaxation or enhancement of BBN constraints on oscillations.
Large enough L alleviates BBN constraints on oscillation parameters.
3+1 oscillations models may be allowed by BBN with L, because large enough L
provides relaxation of BBN constraints, suppressing oscillations and leading to
incomplete thermalization and relaxation of limits on inert neutrino.
Summary

51. Благодаря за вниманието!
Thanks for the attention!

52. Accelerated expansion
Sometime around 5 billion years ago, the universe
began accelerating - its expansion getting faster
and faster, rather than gradually slowing down.
Ordinary matter gravitates.
Antigravity requires unusual medium with p < 0 and
Combined results from CMB, BAO, SN point to the presence of DM and DE.
p/ = ω < -1/3

53. Planck 2013 results
arXiv:1303.5062
Planck and BSM neutrino physics:
No evidence for extra relativistic
neutrino species

54. No compelling evidence for
non-standard number
of neutrino species

55. Sterile Neutrinos Status
• Sterile neutrino is not constrained by LEP
• Required for producing non-zero neutrino masses by most models
• Predicted by GUT models
• Hints from oscillations data: for better fit subdominant sterile oscillations
channel required by Homestake data, Holanda, Smirnov, 2004), Chauhan,
Pulido, 2004, variation of the flux with B, Caldwell D, Sturrock P.,2005
• required for explanation of LSND in combination with other expts
• Wellcomed by cosmology:
* may be the particle accounting for all DM (m<3.5 KeV if MSM produced)
* may play subdominant role as DM component (eV, KeV)
* Fast moving neutrinos do not play major role in the evolution of structure
in the universe.
* may play a role in LSS formation (when constituting few % of the DM it
suppresses small scale power in the matter power spectrum and better fits
the observational data from SDSS, cluster abundance, weak lensing, Lyman
Alpha forest, CMB) Tegmark et al., 2004
*plays major role in natural baryogenesis through leptogenesis

56. Effects of nonequilibrium a  s
Kinetic effects: and  e energy spectrum distortion,
 e depletion, D.K.,1988; Barbieri,Dolgov, 1990,91
Enqvist et.al., 92; DK M.Chizhov, PLB ,1996,97
 energy threshold effect  pre-BBN kinetics
 neutrino-antineutrino asymmetry growth Foot, Volkas,1996; DK M.Chizhov,1996
Dolgov et al., 2002
In case of oscillations effective after  decoupling and provided that the sterile state is not in
equilibrium (Ns<1), kinetic effect on BBN dominate for wide range of oscillation parameters. In
terms of effective number of neutrinos: Nk,0 6 res.osc., Nk,0 3 nonres.
DK , Astrop.Phys.,2003
Kinetic effects and should be appropriately described.
2
~osc
m
Г
E

)(~ 2
EndEEN  
2 2
~ FEГ NG  

57. BBN Summary
Spectrum distortion plays a major role in the influence of neutrino oscillations on BBN.
For oscillations after neutrino decoupling it leads up to 6 times higher helium overproduction
than the dynamical effect of an additional neutrino state.
Distortion decreases with the increase of the initial population of the sterile neutrino, the
kinetic effect decreases correspondingly.
Helium may be both overproduced or underproduced with the increase of the initial
population of s depending which effect dominates (dynamical or kinetic).
Additional partially filled sterile state may lead to strengthening
as well as to relaxation of the BBN constraints.
BBN with nonequilibrium e  s oscillations allows to put constraints
on  oscillation parameters for He-4 uncertainty up to 32%(14%) in resonant
(non-resonant) case, provided s was not in equilibrium, which corresponds
to N<9.
At large mixing BBN constraints strengthen by orders of magnitude when
distortion effect of oscillations is accounted for, at small mixings they are relaxed
due to oscillations generated asymmetry in the resonant case.
Flavor mixing account will lead to a decrease of the spectrum distortion effect
and relaxation of the constraints.

58. 58/27
- Planck satellite will reach a sensitivity for Neff of the order of 0.4 at 2σ
- A detection of a ΔNeff = 0.4 – 0.5 could imply a large degeneracy but
only for almost vanishing θ13, but in this case a measurement of such
angle larger than almost 0.03 would mean extra d.o.f.
- A detection of a ΔNeff > 0.5 would mean in anycase extra d.o.f.
- We have a robust limit from BBN: ΔNeff ≤ 1.2 at 2σ arXiv:1103:1261v1
[astro-ph.CO]

59. Sterile Neutrinos Status
Sterile – that does not couple to standard model W or Z boson.
Hints for sterile from tension with 3 neutrino paradigm: LSND, MiniBooNE,
reactor expts (10-100m), Cr and Ar solar neutrino detectors
cosmology hints: CMB and BBN and LSS
• Wellcomed by cosmology:
• may play subdominant role as DM component (eV, KeV)
• may play a role in LSS formation (when constituting few % of the DM it
suppresses small scale power in the matter power spectrum and better fits
the observational data from SDSS, cluster abundance, weak lensing, Lyman
Alpha forest, CMB)
• plays major role in natural baryogenesis through leptogenesis
• The X ray photons from sterile neutrino decays may catalize the production
H2 and speed up the star formation, causing earlier reionization –
observational feature predicted to search with X-ray telescopes
• Pulsar kicks from anisotropic SN emission
• Sterile neutrino is constrained by BBN, because it increases the expansion
rate and hence dynamically influences He production, in case it is brought
into equilibrium, its decoupling temperature must be TR > 130 MeV.
• In case of oscillations with active neutrino it exerts major effect on
expansion rate and nucleons kinetics during pre-BBN and its mixing
parameters are constrained by BBN+CMB
• Et cetera…..

60. He-4 is the preferred element:
 abundantly produced,
 precisely measured
 precisely calculated (0.1% uncertainty)
Yp=0,2482 0,0007
 has a simple post-BBN chemical evolution
 best speedometer and leptometer
 sensitive to neutrino characteristics (n, N, sp, L..)
BBN with nonequilibrium oscillations leads up
to 32% He overproduction, i.e. N<9.
BBN constraints on the basis of the He-4 data in case proper account for spectrum distortion, δNs
and asymmetry growth due to oscillations were obtained.
BBN constraints, accounting for L, on e s
Barbieri, Dolgov 91 – depletion account
Enqvist et al. 92 – one p approx.
Kirilova, Chizhov 97, 2000 spectrum distortion and L growth
account
Dolgov, Villante, 2003 - spectrum distortion
Kirilova, Panayotova, 2006 – δNs effect
Kirilova, 2010, 2012 – relic L and oscillations generated L
Yp=0,2565  0.001(stat) 0,005(syst)
Izotov&Thuan, 2010 93 Sp of 86 low Z HII
Additional inert population may strengthen
or relax BBN constraints.

61. The dependences of helium production on m2
(for different L) .
lgL=-10
logm2
lgL=-6
lgL=-5
Kirilova JCAP 2012
Relic L and BBN with neutrino oscillations
2
sin 2 1 
lgL
The dependences of helium production on relic L
(for different mixing) .

62. Hamman et al. 2012:
Cosmological data show slight preference
for extra radiation, but 3+2 difficult in LCDM
deviations from minimal model
change in matter density, L ………….